This section provides background information related to the present disclosure whish is not necessarily prior art.
Such a transfer case arrangement is generally known and is used, for example in a motor vehicle, to permanently drive a vehicle axle, e.g. a rear axle, connected to the first output shaft and to additionally transmit, when required, drive torque via the second output shaft to a second vehicle axle, e.g. a front axle. The first vehicle axle permanently driven by the first output shaft is also called the primary axle, whereas the optionally drivable second vehicle axis is called a secondary axle.
The transmission of drive torque via the second output shaft to the secondary axle takes place by an at least partial engagement of the clutch of the transfer case. When the clutch is disengaged, the second output shaft and consequently also the secondary axle are, in contrast, not loaded with drive torque. To prevent unnecessary moments of inertia and drag losses from being generated in that the second output shaft is set into rotation by vehicle wheels connected to the secondary axle, it is known to provide a shutdown device by which the second output shaft can be shut down in that it is decoupled from the vehicle wheels when the clutch is disengaged.
Known transfer cases typically—independent of whether or not they have a shutdown device for shutting down the second output shaft—have a lubrication device for the lubrication of the clutch and/or of another component, e.g. of a bearing, of the transfer case, the lubrication device having a pump for conveying lubrication oil from an oil sump of the transfer case to the clutch and/or to the other component.
Conventionally, the pump is an electrically driven pump or a pump driven by the first output shaft, for example a gerotor pump, which continuously conveys lubrication oil.
Such pumps result in a deterioration of the efficiency of the transfer case so that pump-less lubrication devices have been developed which convey lubrication oil from the oil sump to the clutch and/or bearings of the transfer case while utilizing a chain drive or a gear connection between the output of the clutch and the second output shaft.
If such pump-less lubrication devices are provided in a transfer case arrangement with a shutdown device, the problem, however, occurs that no lubrication oil is conveyed when the second output shaft is shut down. This impairs the lubrication of the clutch and/or of the bearings of the transfer case and can result in damage to the transfer case at least in the long term.